Crane construction



Sept. 20, 1938. FOLEY 2,130,487

CRANE CONSTRUCTION Filed Sept. 14, 1936 Er f E F;

INVENTOR." 7710/7/43 (Q ICOLEX ATTORNEY.

' of the crane.

Patented Sept. 20, 1938 UNITED STATES PATENT OFFICE CRANE CONSTRUCTION Thomas A. Foley, Astoria, N. Y. Application September 14, 1936, Serial No. 100,645 9 Claims. '(ci. 21e 49) This invention relates to cranes and in particular to caterpillar tractor cranes in which is provided a folding gantry and an adjustable counterweight.

An object of the invention is to provide, in a crane of the character referred to, a folding gantry over which the boom cables pass instead of being secured thereto as in present day construction.

A further object of the invention is to provide a counterweight which is automatically operable to compensate for the weight lifted by the boom In boom type cranes of present day construction, where the crane is mounted for movement from place to place as work progresses, it is necessary to dismantle the crane in order that it will passunder tunnels, wires and other obstructions and the dismantling requires the taking down of a solid'rig on top the crane to which the boom cables are attached. This type of rig or solid gantry prevents the use of the crane under low bridges as the crane cannot be taken beneath such structures, and also necessitates dismantling when the crane is loaded on a flat car or truck for shipment. It is an object of the prsent invention therefor, to provide a gantry which is foldable, can be collapsed with a minimum of time and has an important place in the operation of the crane. As is well known,

the sharper the angle between boom and boom cable, the greater the power required to manipulate the boom, and in solid gantry construction, this angle gets sharper as the boom rises and in many instances has caused buckling of the boom under compression. With my foldable gantry, the boom cables are secured to the crane behind the gantry and pass thereover, so that the usual working or hinge angle of cable and boom is maintained until the boom raises so that the cables leave the gantry and maintain the angle even when the boom is in erect position. This affords an advantage in that the boom can be used for picking up heavier loads in its vertical position without fear of buckling the boom and in moving the crane from one location to another the cables do not have to be detached from the crane, the gantry being merely folded to lower the superstructure sufliciently to get the benefit derived in present day cranes by complete dismantling.

In the caterpillar type of crane, the crane is mounted for rotation on a center pin and this pin takes a great amount of the thrust of the load being lifted. A crane must be heavier than the load it lifts in order that it will not turn over. I have provided an adjustable counterweight mounted at the rear of the crane which raises and lowers in accordance with the raising or lowering movement of the main boom to relieve the strain on the center pin, to increase the capacity of the crane by permitting it to lift about one third more weight than the crane weighs, to eliminate the use of 'outriggers and to prevent the crane from tipping over. I v While I have illustrated a caterpillar type of crane it is to be understood that my improvements are applicable to any type of crane of the fixed or mobile type, and the gantry can be employed without the counterweight although they both operate in unison to make the crane more eflicient and easier to handle.

Changes and variations may be made-in the construction shown and described without departing from the principles of the invention or sacrificing its chief advantages; hence such invention is not confined to the precise structures shown in the drawing, in which:

Figure 1 is a view in side elevation of a caterpillar tractor crane in which are incorporated my improvements, one outline position of the crane boom and cable being illustrated,

Figure 2 is a diagrammatic view of a crane as shown in Figure 1, in which the gantry has been swung down to non-use position and the boom cables accordingly lowered to permit the movement of the crane under low structures,

Figure 3 is a view similar to Figure 2 in which the crane is shown lifting a load and the counterweight is automatically positioned to offset the effect of the load,

Figure 4 is a view in perspective showing the arrangement of the boom cables and the mounting of the swinging or folding gantry,

Figure 5 is a view in diagrammatic perspective showing the arrangement of counterweight and counterweight boom cables as employed at the rear of the crane,

Figure 6 is a view in side elevation ing gantry, the folded position thereof being shown in outline,

Figure 7 is a view in side elevational section as seen on the line 1-1 of Figure 8 showing the means for actuating the main boom cables and the counterweight cables, and

Figure 8 is a view in front elevation of the mechanism illustrated in Figure 7.

Referring to the drawing in detail, l0 indicates a cab of a caterpillar tractor crane which is mounted for rotation on the center pin l I secured of the swingor mounted to the tractor member l2 in the well known manner, the cab having a frame |3 to which the main boom I4 is pivoted for raising and lowering movement, said frame also supporting the usual counterweight found in all cranes for offsetting the load lift, this counterweight which will hereafter be referred to as the counterbalance being indicated'by the numeral I. The boom I4 is raised and lowered by the cable It which is wound about the drum l'l interiorly of the cab, and passing over asheave il in the roof of the cab, coacts with cable l3 and pulley train 23 in actuating the boom l4. The pulley train 20, through the medium of the cables 2| is secured as at 22 to the frame H at the rear of the roof of the cab Ill and pass over the rollers 23 of a swinging gantry 24.

The gantry 24 consists of the forwardly ex tending arms 24A pivotally mounted in the brackets 25 secured to the frame I3 and connected by the laterally extending bar 26, to which is also pivotally secured, the rearwardly extending legs 21 which are readily detachable from the brackets 28 on the rear of frame l3 by the pins 29. Through this latter means, the gantry can be readily folded. When the crane is to be moved,

the boom i4 is raised until the cables 2| clear the gantry 24. Then the pins 23 are withdrawn and the gantry can be collapsed or folded flat onto the roof of the cab as illustrated in Figures 2 and 6. The boom is then lowered as in Figure 2 and the crane can be moved under low bridges or placed on a flat car or truck for transportation. As set forth the gantry 24 provides a support over which the main boom cables 2| pass so that a maximum effective working angle of boom and boom cable can be maintained. As the cable leaves the gantry, the same efjective angle is maintained whereas in the present day type where the cable is secured to the top of a fixed gantry the angle of boom and cable becomes sharper, the cable and boom are subjected to greater stress and the liability of damage is increased. The effectiveness of the folding gantry is illustrated in Figure 1, where the effective angle of boom and cable is maintained as the cable leaves the gantry as shown in outline.

In order to increase the load lifting capacity of the crane, I have pivotally mounted at the rear of the frame i3, a counterweight boom 30 which supports a counterweight 3|, the weight and boom being actuated by the cables 32 and 33 respectively. The cable 32 is operated by a drum 34 known as the counterweight drum while the cable 33 is operated by counterweight boom drum 35. The purpose of this mechanism is to automatically increase the equilibrium of the crane by enlarging its base area as the load to be lifted by the main boom increases. As illustrated in Figure 3, the stress on the center pin II is greatest as the main boom assumes its horizontal position and the greatest liability to overturning or tilting of the crane is present at this time when the crane is picking up a load L. The counterweight. at this time, and its boom are extended a maximum amount and as the main boom raises, the counterweight boom raises in proportional amount to offset the lift strain on the crane'and particularly on the center pin as lifting and swinging of the load takes place. The counterweight and its boom therefore, take the strain of! the pin II and by increasing the balance of the crane enlarge its weight lifting capacity in proportion to the weight of the crane itself. The diameters of the boom and counterweight drums boom 33 raises the weight 3| swings toward the crane on a horizontal line and outwardly therefrom in horizontal line as the boom lowers. This combined action of the counterweight 3| and boom 33 takes place automatically and simultaneously with the operation of the.main boom l4, through the medium of mechanism to be described.

The drums 34 and 35 are mounted for free rotation on the counterweight shaft 36 to which is secured the worm-wheel 3'|"for operating said shaft 33. The rotation of the shaft 33 is transferred to the drums 34 and 35 by the clutches 33 and 33 respectively, which may be adjusted by the clutch levers 40, the clutches being splined to the shaft 33. During ordinary operation of the crane the clutches are in engagement with the drums 34 and 35, but in order to provide for relative adjustment of the weight 3| and boom 33, the respective drums are provided with ratchet wheels 4| and dogs 42 which can hold the drums stationary or permit the adjustment thereof when the clutches are free. The dogs are held out of contact with the ratchet wheels by pins 43, or other suitable means. The drums operate so that the counterweight boom cable 33 is reeled in as the counterweight cable 32 is payed out. As the boom raises, the cable 32 must keep the weight at the same level.

The worm wheel 31 derives its power from the worm 44 mounted on the shaft 45 carrying at its lower end the bevel pinion 46 which is in mesh with the reversing bevel gears 41 mounted for free rotation on the drive shaft 43. The operation of the gears 41 is controlled by the sliding clutches 49 splined to the shaft 43 and arranged for alternate engagement with the bevel gears 41 by the clutch lever 50. The drive shaft 48 through the medium of a gear train 5| is driven from any suitable power source such for instance as an internal combustion engine or electric motor 52. Positioned between the bevel gears 41 is the pinion 53 which operates the worm and worm-wheel connection to the main boom cable drum as at 54, the drum ll being mounted for rotation with the shaft i5 operated by said worm drive 54.

My invention is not to be restricted to the precise details of construction shown since various changes and modifications may be made therein without departing from the scope of the invention or sacrificing its chief advantages.

What I claim is:

1. In a crane, in combination, a frame, a main boom pivoted for raising and lowering movement, an auxiliary boom, a counterweight supported by said auxiliary boom, means for raising and lowering said auxiliary boom and said main boom, and said means being operable in unison to raise both booms whereby a load on the main boom is counterbalanced by said counterweight of the auxiliary boom, a gantry over which the main boom raising means passes, said means being free of the gantry when the main boom is raised to a certain position, and said gantry being ioldable when the said means is free therefrom.

2. In a crane, in combination, a main boom, an auxiliary boom, a counterweight carried by the axillary boom, and means for raising and lowering both of the booms and moving the counterweight simultaneously, a gantry over which the main boom raising means passes, said means being free of the gantry when the main boom is raised to a certain position, and said gantry being foldable when the said means is free therefrom.

3. In a crane, incombination, a main boom, an

uxiliary boom, a counterweight suspended from passes, said means being free of the gantry when, the main boom is raised to a certain position and said gantry being foldable when the said means is free therefrom.

4. In a crane, in combination, a main boom, an auxiliary boom, a counterweight on the auxiliary boom, means for actuating the booms and the counterweight simultaneously to compensate for a load picked up by said main boom, and said means maintaining the counterweight at the same height from the ground in all actuated positions thereof.

5. In a crane. in combination, a frame, a main boom, an auxiliary boom,

when the boom is in other 8. In a crane, in combination, a main boom, an auxiliary boom, a counterweight for offsetting the load eflect or? the main boom on the stability ofthe crane, cable means for supporting the main boom. the eronliary boom and the countercable passes and from which it is free in certain positions of the boom and means for folding the gantry when the cable is free therefrom.

7. In a crane, in combination, a main boom, an auxiliary boom, a counterweight for offsetting the tilting effect of a loaded main boom on the crane, cable means for moving the main and auxiliary booms and the counterweight in unison including cable drums, a drive shaft, a drum shaft on which the drums are mounted, connections between the drive shaft and the drum shaft whereby the latter is operated, said connections including a drive reversing mechanism, and one of the drums being relatively smaller than the other drums whereby the-counterweight is maintained at a fixed horizontal level during its movement.

8. In a crane, in combination, a frame, a weight in the frame providing a balance, a main boom, and an auxiliary boom both mounted for pivotal movement on the frame, a counterweight on the a boom, cable means for raising and lowering both of the booms and for moving the counterweight toward and away from the crane horizontally, and means for operating the cable means in unison.

9. In a caterpillar tractor crane, in combination, a main boom, an auxiliary boom, a counterweight for increasing the lifting capacity of the main boom without tilting the crane, cable means for operating the main and auxiliary booms and moving the counterweight horizontally, and actuating means for said cable means whereby said cable means may operate the booms and counterweight in unison, a gantry over which the main boom operating cable means passes and from which said cable means is free in certain positions, and means for folding the gantry when the cable means isfree therefrom.

THOMAS A. FOLEY. 

